Field
The disclosed embodiments relate to battery chargers for portable electronic devices. More specifically, the disclosed embodiments relate to techniques for performing battery detection via voltage regulation of battery terminals in portable electronic devices.
Related Art
Portable electronic devices, such as laptop computers, portable media players, and/or mobile phones, typically operate using a rechargeable battery. Furthermore, designs for such batteries often include battery packs that contain battery cells connected together in various series and parallel configurations. For example, a six-cell battery pack of lithium-polymer cells may be configured in a three in series, two in parallel (3s2p) configuration. Hence, if a single cell can provide a maximum of 3 amps with a voltage ranging from 2.7 volts to 4.2 volts, then the entire battery pack can have a voltage range of 8.1 volts to 12.6 volts and provide 6 amps of current.
A battery in a portable electronic device is typically managed by a circuit, which is commonly known as a battery management unit (BMU). The BMU may be integrated into the battery pack of the portable electronic device and perform functions such as gauging the battery's capacity and/or providing electrical protection for the battery. For example, the BMU may open a protection circuit that disconnects the battery from the portable electronic device upon detecting a fully depleted battery and/or an overvoltage situation that may damage the battery.
By opening the protection circuit, the BMU may interfere with detection of the battery from the portable electronic device. For example, a charger in the portable electronic device may be unable to differentiate between a missing battery and a battery with an open protection circuit, which has the same voltage as the missing battery when measured from the portable electronic device. The charger may further be unable to determine if the battery is connected to or disconnected from the portable electronic device. As a result, the charger may attempt to charge a non-existent battery and/or a battery with an open protection circuit, which may result in a system voltage collapse and/or a system reset in the portable electronic device.
Consequently, use of batteries with portable electronic devices may be facilitated by mechanisms for detecting the presence of the batteries in the portable electronic devices, even if the protection circuits of the batteries are open.